Why is July 31 not the deadline for all taxpayers?

For most people, or those who file ITR-1 or ITR-2, the deadline is July 31. However, people who don't get their accounts audited, like freelancers, consultants, professionals and small business owners, have August 31 as their due date. These are individuals who file ITR-3 or ITR-4. Meanwhile, those whose accounts have to be audited have an October 31 deadline.